Vacuum insulation panel

Abstract

Vacuum insulation panels, methods for manufacture thereof, and applications thereof are described. The vacuum insulation panels comprise a porous insulating core encapsulated in an envelope to which a vacuum is applied. The envelope is coated with a waterproof coating layer which increases the robustness of the vacuum insulation panel.

Claims

1. A vacuum insulation panel comprising: (a) a porous insulating core having an upper surface and a lower surface and sides; (b) an envelope about the core arranged to envelop the core, and to maintain an applied vacuum within the envelope; and (c) a non-foam polyurethane coating layer applied to the envelope, wherein the coating layer is formed over the entire surface area of the envelope, the polyurethane coating layer is less than about 5 mm thick and (d) the envelope and the polyurethane coating layer form a barrier layer about the insulating core, the barrier layer having a moisture vapour transmission rate of from about 1.5×10.sup.−3 g/m.sup.2.Math.day to about 3.0×10.sup.−3 g/m.sup.2.Math.day when measured in accordance with ASTM F1249-90.

2. The vacuum insulation panel according to claim 1, wherein the envelope comprises a metallised film.

3. The vacuum insulation panel according to claim 1, wherein the polyurethane coating layer is from about 0.1 mm to about 3 mm thick.

4. The vacuum insulation panel according to claim 1, wherein the polyurethane coating layer has a vapour resistivity of from 5000 MN.Math.s/gm to 100000 MN.Math.s/gm or more.

5. The vacuum insulation panel according to claim 1, wherein the polyurethane coating layer is formed from a polyurethane resin composition comprising a first isocyanate containing part and a second polyol containing part.

6. The vacuum insulation panel according to claim 1, wherein the barrier layer has a moisture vapour transmission rate of about 2.5×10.sup.−3 g/m.sup.2.Math.day or less, when measured in accordance with ASTM F1249-90.

7. The vacuum insulation panel according to claim 1, wherein the barrier layer having an oxygen transmission rate of from about 2×10.sup.−3 cc/m.sup.2.Math.day to about 5×10.sup.−3 cc/m.sup.2.Math.day when measured in accordance with ASTM D3985.

8. The vacuum insulation panel according to claim 1, wherein the barrier layer having a moisture vapour transmission rate of about 2.5×10.sup.−3 g/m.sup.2.Math.day or less, and an oxygen transmission rate of about 4×10.sup.−3 cc/m.sup.2.Math.day or less.

9. The vacuum insulation panel according to claim 1, wherein the porous insulating core is constructed from a microporous powder material selected from silica, fumed silica and/or precipitated silica, perlite, diatomaceous earth and combinations thereof.

10. The vacuum insulation panel according to claim 1, having a thermal conductivity of from 3.0 mW/(m.Math.K) to 4.5 mW/(m.Math.K).

11. The vacuum insulation panel according to claim 1, further comprising at least one reinforcing member arranged on the upper or lower surface of the insulating core to reinforce the core, wherein the reinforcing member is formed of a porous material, and is substantially rigid; wherein together the at least one reinforcing member and the insulating core form a hybrid core and the reinforcing member(s) do not form a thermal bridge across the insulating core; and wherein the envelope is arranged to envelop the hybrid core.

12. The vacuum insulation panel according to claim 11 having an upper reinforcing member arranged on the upper surface of the insulating core and having a lower reinforcing member arranged on the lower surface of the insulating core.

13. The vacuum insulation panel according to claim 11 wherein the at least one reinforcing member comprises a metal foil facer, the metal foil facer having a thickness of from 4 microns to 50 microns, and extending across substantially the entire surface of the reinforcing member, on the upper surface or lower surface thereof and wherein the metal foil facer does not form a thermal bridge between the upper surface and lower surface of the reinforcing member.

14. The vacuum insulation panel according to claim 11, wherein the density of the insulating core within the vacuum insulating panel is of from 100 kg/m.sup.3 to 160 kg/m.sup.3.

15. The vacuum insulation panel according to claim 11, wherein the at least one reinforcing member(s) has a density that is lower than that of the insulating core.

16. The vacuum insulation panel according to claim 11, further comprising at least one metal foil having a thickness of from 4 microns to 50 microns, between the envelope and the insulating core and extending across substantially the entire surface of the insulating core on the upper surface or lower surface thereof and wherein the foil does not form a thermal bridge between the upper surface and lower surface of the insulating core.

17. The vacuum insulation panel according to claim 16, wherein the metal foil is attached to the inside of the envelope.

18. The vacuum insulation panel according to claim 17, wherein the envelope comprises an envelope inner layer and the metal foil has at least one outer layer attached thereto wherein the envelope inner layer and the outer layer on the metal foil are attached to each other being optionally bonded to each other.

19. The vacuum insulation panel according to claim 16, comprising two metal foils having a thickness of from 4 micron to 50 micron, wherein one metal foil extends across substantially the entire surface of the core on the upper surface and a second metal foil extends across substantially the entire surface of the core on the lower surface.

20. The vacuum insulation panel according to claim 1, further comprising a layer of adhesive on the outer surface of the panel.

21. The vacuum insulation panel according to claim 20, wherein the adhesive is a pressure sensitive adhesive.

Description

DRAWINGS

(1) Embodiments of the disclosure will be described, by way of example only, with reference to the accompanying drawings in which:

(2) FIG. 1 is perspective cut-away view of a vacuum insulation panel in one aspect of the disclosure;

(3) FIG. 2 is a cross-sectional view of a view of a vacuum insulation panel comprising a hybrid core;

(4) FIG. 3 shows a cross-sectional view of a vacuum insulation panel comprising an alternative hybrid configuration to the vacuum insulation panel of FIG. 2;

(5) FIG. 4 shows a perspective cut away perspective view of the vacuum insulation panel of FIG. 2;

(6) FIG. 5 shows a cut away perspective view of a vacuum insulation panel comprising a hybrid core, having metal foil facers on the reinforcing members;

(7) FIG. 6 shows a cut away perspective view of a vacuum insulation panel comprising metal foil layers disposed between the insulating core and the envelope;

(8) FIG. 7 shows the vacuum insulation panel of FIG. 6 further comprising a fleece encasing the insulating core;

(9) FIG. 8 shows a cross-sectional view of the vacuum insulation panel shown in FIG. 6;

(10) FIG. 9 shows a perspective cut away view similar to FIG. 6, with enhanced views of the metal foil and the envelope;

(11) FIG. 10 shows a cross-sectional view showing the construction of the envelope structure;

(12) FIG. 11 shows a cross-sectional view showing the construction of the metal foil;

(13) FIGS. 12A and 12B show a cross-sectional view depicting the method of sealing the envelope of a vacuum insulation panel;

(14) FIG. 13 is a cross-sectional view depicting the sealed edge of the envelope of a vacuum insulation panel;

(15) FIG. 14 is a perspective and cross-sectional view of a vacuum insulation panel;

(16) FIG. 15 is a perspective view of a vacuum insulation panel of the present disclosure.

DETAILED DESCRIPTION

(17) All thermal conductivities values referenced herein are those determined under BS EN: 12667:2001 unless expressly indicated otherwise. All thermal conductivity values expressed herein are measured in Watts per meter Kelvin or milliwatts per meter Kelvin.

(18) All oxygen transmission rate (OTR) values referenced herein are measured according to ASTM D3985 (measured at 23° C. with 50% relative humidity) and all moisture vapour transmission rate (MVTR) values referenced herein are measured according to ASTM F1249-90 (measured at 38° C. with 100% relative humidity).

(19) All vapour resistance vapour resistivity values and vapour resistivity values referenced herein are measured according to standard EN 12086. The unit of vapour resistivity is Mega-Newton seconds per gram-metre, MN.Math.s/gm. The unit of vapour resistance is Mega-Newton seconds per gram.

(20) All viscosity values referenced herein are measured according to standard BS188. The units of viscosity is millipascal second, mPa.Math.s.

(21) Unless otherwise specified compressive strengths are measured as according to BS EN 826: 2013. The unit of compressive strength is the kilopascal, kPa.

(22) FIG. 1 is a perspective cut-away view of a VIP 1 according to the present disclosure. FIG. 1 shows a porous insulating core 3, having an upper surface 301 and a lower surface 302 and sides 303a-303d. An envelope 2 about the insulating core 3 is arranged to envelop the core, and to maintain an applied vacuum within the envelope 2. A fleece 5 is shown encasing the insulating core 3. A non-foam polyurethane coating layer 4 is applied to the exterior of the envelope 2. The non-foam polyurethane coating layer is formed over the entire external surface area of the envelope 2.

(23) FIG. 2 is a cross-sectional view of a VIP 1 of the disclosure. The VIP 1 comprises an insulating core 3 having upper 301 and lower 302 surfaces. The VIP also comprises a reinforcing member 6a of rigid polyurethane arranged on the upper surface 301 of the core 3. A second reinforcing member 6b of rigid polyurethane is arranged on the lower surface 302 of the core 3. The reinforcing members 6a & 6b are suitably constructed from a cellular material, such as a foam. The reinforcing members are porous and have a substantially smooth outer surfaces 601a & 601b. Together the reinforcing members 6a & 6b and the insulating core 3 form a hybrid core 7. The reinforcing members 6a, 6b are arranged so that no thermal bridge is formed across the insulating core 3 i.e. the reinforcing members do not form a thermal bridge between upper surface 301 of the insulating core and lower surface 302 of the insulating core. The upper surface 601a of the upper reinforcing member 6a is substantially smooth as is the lower surface 601b of the lower reinforcing member 6b. The VIP further comprises a barrier envelope 2, optionally constructed from a barrier film, arranged to envelop the insulating core 3 and the reinforcing members 6a, 6b of the hybrid core 7. The barrier envelope 2 is coated with a non-foam polyurethane coating layer, which coats the entire external surface of the envelope. The insulating core comprises microporous fumed silica. The density of the insulating core in this embodiment is 130 kg/m.sup.3.

(24) FIG. 3 shows an alternative configuration wherein one reinforcing member 6b is present and extends substantially across the entire lower surface 302 of core 3. In this embodiment the reinforcing member 6b and the insulating core 3 together form a hybrid core 7. The insulating core comprises microporous fumed silica. The density of the insulating core in this embodiment is 140 kg/m.sup.3.

(25) FIG. 4 shows a perspective cut away view of a VIP 1 according to the present disclosure. In the embodiment shown, the VIP comprises two reinforcing members 6a and 6b. The insulating core 3 is shown encased in a fleece 5. Fleece 5 is an optional component, and may have greater of lesser utility depending on the method of manufacture of the VIP.

(26) FIG. 5 shows the embodiment of FIG. 4 wherein the upper reinforcing member 6a further comprises a metal foil facer 8. The metal foil facer may have a thickness of from 4 microns to 50 microns. In the embodiment shown in FIG. 5, the metal foil facer has a thickness of 12 microns. As clearly depicted in FIG. 5, the metal foil does not form a thermal bridge between the upper surface 602a and the lower surface 602b of the reinforcing member 6a.

(27) Advantageously, one or both upper and lower reinforcing members may comprise a metal foil facer. The reinforcing member may for example be a polyurethane foam blown on a metal foil facer. Additionally or alternatively the metal foil facer may be adhered or affixed to a reinforcing member formed from a sheet of polyurethane foam.

(28) FIG. 6 shows VIP 1 as a further embodiment of the disclosure. Corresponding features are numbered as in the foregoing description. VIP 1 is shown comprising a porous insulating core 3, having an upper surface 301 and a lower surface 302 and sides 303a-303d. An envelope 2 about the insulating core 3 is arranged to envelop the core, and to maintain an applied vacuum within the envelope 2. A non-foam polyurethane coating layer 4 is applied to the exterior of the envelope 2. The polyurethane coating layer is formed over the entire external surface area of the envelope 2. A metal foil 9 having a thickness of at from 4 microns to 50 microns is disposed between the envelope 2 and the core 3. A metal foil 9a extends across substantially the entire upper surface 301 of the core, without forming a thermal bridge between the upper surface 301 and the lower surface 302 of the core. A second metal foil 9b extends across substantially the entire lower surface 302 of the core, without forming a thermal bridge between the lower surface 302 and the upper surface 301 of the core. Neither the metal foil 9a, nor the metal foil 9b are attached to the core 3.

(29) FIG. 7 is a perspective cut-away view of a VIP analogous to that shown in FIG. 6, however, a fleece 5 is shown encasing the insulating core 3. One metal foil 9a is shown atop the fleece 5, on the upper surface 301 of the insulating core 3. A second metal foil 9b is shown below the fleece 5, on the lower surface 302 of the insulating core 3. Neither 9a nor 9b are attached to the core or the fleece 5.

(30) FIG. 8 is a cross-sectional view of a VIP according to the present disclosure. FIG. 8 clearly shows the metal foil 9 disposed between the insulating core 3 and the envelope 2. The non-foam polyurethane layer is shown entirely coating the envelope 2. FIG. 8 shows a metal foil 9a extends across substantially the entire upper surface 301 of the core, without forming a thermal bridge between the upper surface 301 and the lower surface 302 of the core. FIG. 8 also shows a second metal foil 9b which extends across substantially the entire lower surface 302 of the core, without forming a thermal bridge between the lower surface 302 and the upper surface 301 of the core. In some embodiments only metal foil may be present.

(31) It will be noted that the foils 9a and 9b are not attached to the core 3. Instead they are initially separate from the envelope 2 and the core 3 and are later attached to the envelope 2 as will be described below.

(32) FIG. 9 is a perspective view of a VIP according to the present disclosure, similar to that of FIGS. 6 to 8, with an enlarged view of the envelope 2 shown as an envelope structure 201 and an enlarged view of the foil 9a shown as a metal foil structure 901. (It will be appreciated that even though there are two separate foils 9a and 9b each may have the same structure.) The enlarged view of the envelope structure 201 shows three metalized films 10. Each metalized film 10 is a metalized plastic layer of for example metalized PET. Suitably, metalized polypropylene (PP) or metalized EVOH (ethyl vinyl alcohol) may also be employed. The metalized films 10 are attached to an envelope inner layer 11. The envelope inner layer 11 is typically a thermoplastic polymer, such as polyethylene. Suitable alternatives include low density polyethylene (LDPE) e.g. linear low density polyethylene (LLDPE), and ultra-high molecular weight polyethylene (UHMWPE); polypropylene and ethylenevinyl alcohol (EVOH), polyvinylidene chloride (PVDC); thermoplastic urethanes; including combinations thereof including copolymers and blends thereof.

(33) The enlarged view of the metal foil structure 901 shows the metal foil 9a with an outer layer 12 attached thereto. The outer layer 12 is typically a thermoplastic polymeric material, for example polyethylene.

(34) FIG. 10 is a cross-sectional view showing the construction of the envelope structure 201. The layers of metalized film 6 are bonded together for example to form a laminate 61. Each layer (i.e. polymer film and metal applied to it taken together) is typically about 12 micron thick. The laminate structure is bonded to an inner envelope layer 7 of thermoplastic material, for example a layer of polyethylene.

(35) FIG. 11 is a cross-sectional view showing the construction of the metal foil structure. The metal foil 9 is typically aluminum foil. The metal foil 9 is attached to an outer layer 12 of thermoplastic material, for example a layer of polyethylene. Optionally the metal foil 9 is attached to an inner layer 13 of a suitable polymer, for example PET.

(36) FIGS. 12A and 12B show a cross-sectional view depicting method of sealing and the seal obtained when a VIP envelope is sealed. The skilled person will appreciate that the VIP is sealed, prior to the non-foam polyurethane coating layer being applied to the envelope, so as to coat the entire (external) surface area of the envelope.

(37) As shown in FIG. 12A heating irons or jaws 501a and 501b are employed to grip opposing sides (upper side grip 502a and lower side grip 502b) of the envelope 2 bringing them together and said jaws apply heat to the edges 503a (upper edge) and 503b (lower edge) of the opposing sides 504a (upper side) and 504b (lower side) of the envelope 2. An inner layer of polymer 11 on the inside surface 505 of the envelope 2, between the edges 503a and 503b gripped by the heating jaws 501a and 501b, softens sufficiently, to form a bond 601 between the edges 503a and 503b of the envelope 2 in contact with each other between the heating jaws 501a and 501b (see FIG. 12B). Only the inner layer of polymer 11 exposed to the application of heat softens to for a bond or seal 601 between the edges 503a and 503b. The application of heat from the heating irons or jaws 501a and 501b to the edges of the envelope 503a and 503b, does not soften the inner layer of polymer 11 substantially beyond the gripped edges 503a and 503b of the envelope 2. Hence, the application of heat from heating jaws 501a and 501b does not cause proximate edge portions 603a and 603b to bond to each other. Furthermore, the metal foils 9 within the evacuated VIP 1 are not attached to the inner layer of the envelope at this stage in production.

(38) FIG. 13 is a cross-sectional view depicting the seal 602 obtained when the envelope 2 of a VIP according to the present disclosure is sealed. Similar to the method described in relation to FIG. 12A and FIG. 12B above, heating jaws 501a and 501b apply heat to bond the edges 503a and 503b of the envelope 2 of VIP 1. As described above, seal 601 is formed by application of heat from heating jaws 501a and 501b to said edges. The entire VIP is subsequently heated to attach each of the metal foils 9 to the inner layer 11 of the envelope 2. As shown in the enhanced view 801 of FIG. 14 once the entire VIP 1 is heated, the inner layer 11 of the envelope 2 softens as does the outer layer 12 on the metal foil 9, thereby forming a bond 701 between the metal foil 9 and the envelope 2. The skilled person will appreciate that while the entire upper metal foil 9a and the entire lower metal foil 9b are not shown in FIG. 13, at least one or both may be present. In addition, by heating the entire VIP, to attach the inner layer 11 of the envelope 2 to the metal foil 9, the inner layer 11, at proximate edges 603a and 603b of the envelope 2, which were not directly exposed to the heat of the heating jaws 501a and 501b, soften sufficiently, to provide an enhanced edge seal 602 about the envelope 2. It will be appreciated that not only does the vacuum assist with bonding of the metal foil(s) 9 to the envelope but also in drawing together the parts of the envelope about the initial seal, and in particular those on the interior side, i.e. the vacuum side, of the initial seal. Accordingly, VIPs of the present disclosure have an improved envelope seal in comparison to those of traditional VIPs. An enhanced seal increases the longevity of the VIP and contributes to an improved aged thermal performance of the VIP.

(39) FIG. 14 is a perspective cross-sectional view of a VIP according to the present disclosure prior to application of the non-foam polyurethane coating layer, showing the envelope seal 901 at the sides of the VIP (only the envelope seal proximate sides 303b and 303d of the insulating core 3 are shown). FIG. 15 clearly shows the metal foils 9a and 9b disposed between the insulating core 3 and the envelope 2. 902 shows how the metal foil 9a is arranged so as not to form a thermal bridge across the insulating core, as the metal foil does not wrap around the sides 303a-303d of the insulating core. FIG. 15 shows the VIP according to the present disclosure prior to folding and taping the edges, and prior to application of the non-foam polyurethane coating.

(40) FIG. 15 is a perspective view of a VIP 1 according to the present disclosure, wherein the edge seals have been folded and taped to provide a substantially cuboid finished VIP, and a non-foam polyurethane coating layer has been applied to the envelope, coating the entire (external) surface area of the envelope.

(41) The ability of a VIP envelope to maintain a defined vacuum during the lifetime of a VIP is of great importance in achieving and maintaining long-term thermal performance. Thermal edge effects occur due to the relatively high thermal conductivity of the envelope material which envelops the insulating core. Thermal edge effects are observed because the envelope acts as a thermal bridge around the insulating core, which has a very low thermal conductivity, once a vacuum is maintained, within the VIP.

(42) Choosing a material suitable for a VIP envelope is therefore a balance between selecting a material with a desirably low thermal conductivity and a low permeation. Metalized films as described above which are employed as envelopes in traditional VIPs have a reasonably low thermal conductivity. However, their permeability substantially reduces the lifetime and therefore, overall utility of traditional VIPs.

(43) The thermal conductivity of aluminium is 167 W/(m.Math.K). Accordingly, aluminium is not a suitable material for a VIP envelope, due to the high edge effects which would be observed as a consequence of aluminium's high thermal conductivity value. However, aluminium foils have excellent barrier properties.

(44) VIPs of the present disclosure comprising a metal foil layer of from 4 microns to 50 microns, provide a significant advancement over prior art VIPs. Such VIPs marry the desirable low thermal conductivity properties of traditional VIP envelopes with the desirable low permeability properties of metal foils.

(45) For the embodiments shown in FIGS. 5 to 15, after a vacuum is applied and the edge of the VIP is sealed, the metal foil disposed between the inner surface of the envelope and at least the upper surface of the insulating core, whether in the configuration shown in FIG. 5, or as shown in FIGS. 6 and 7 is attached to the inner surface of the envelope. For example, the metal foil may be attached to an outer layer of thermoplastic material, such as polyethylene and the envelope may have an inner envelope layer made of a thermoplastic material, such as polyethylene. As the VIP is evacuated the outer surface on the metal foil will be in close proximity to the inner surface of the envelope inner layer. When the VIP is heated, for example in an oven, to a temperature sufficiently high to soften the thermoplastic materials, the metal foil becomes attached to the inside surface of the envelope. The metal foil is arranged so as not to form a thermal bridge across the insulating core. However, the excellent low permeation properties of the foil significantly improve the permeation properties of the VIP. Accordingly, the lifetime of the VIP is significantly increased. It will be appreciated that the attachment of the foil to the envelope can be done after the VIP has been formed and in particular after any vacuum source has been removed. The vacuum retained within the envelope will assist in joining the foil to the envelope. Effectively the pressure differential between atmospheric pressure to the exterior of the VIP and the retained (reduced) pressure within the VIP imparts a force pressing the envelope towards the foil (and the core). And of course this force is imparted uniformly across the envelope. This is ideal for uniform joining of the envelope to the foil.

(46) The procedural step of heating the evacuated VIP in an oven also improves the original heat seal at the edge of the envelope.

(47) Because the envelope of a VIP is traditionally sealed between heating jaws as described above, only the area of the envelope directly exposed to the heat of the heating jaws is heated sufficiently in order to melt the thermoplastic inner envelope layer and join the two proximate edges. Edges of the envelope in close proximity which have not been exposed to elevated temperature are not joined/bonded.

(48) In contrast, in the embodiment described above, whereby the metal foil of a VIP according to the present disclosure is attached to the inner surface of the VIP envelope, by heating the entire VIP (post evacuation), edges of the envelope which are proximate, which were not originally bonded by the heating jaws, remain proximate due to the external pressure applied to the evacuated VIP and when heated the thermoplastic layers of said edges soften and a bond is formed therebetween.

(49) Thus while the presence of the metal foil attached to the envelope, provides an ultra-low permeation envelope, the seal of the VIPs of the present disclosure are considerably enhanced, in comparison to those of traditional VIPs, accordingly, the lifetime of the VIPs of the present disclosure are significantly longer than traditional VIPs without reducing the thermal performance.

(50) The VIP envelopes shown in FIGS. 5 to 15 have an oxygen transmission rate of about 4×10.sup.−3 cc/m.sup.2.Math.day and a moisture vapour transmission rate of about 2.5×10.sup.−3 g/m.sup.2.Math.day.

(51) The presence of the non-foam polyurethane coating substantially increases the robustness of the VIP. The polyurethane coating provides a protective coating on the outer surface of the VIP which provides the VIP with a waterproof coating, and also increases the barrier protection, making accidental perforation of the VIP less likely. Accordingly, the VIPs of the present disclosure, are less susceptible to damage, for example when stored on site, prior to installation.

(52) Suitably, the non-foam polyurethane coating provides excellent wear resistance and long term durability to the VIP. For example, the polyurethane coating may in addition to providing waterproofing, also provide resistance to damage from UV rays or resistance to corrosive materials such as acidic materials. Suitably, the polyurethane coating is flexible and crack resistant.

(53) The words “comprises/comprising” and the words “having/including” when used herein with reference to the present disclosure are used to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

(54) It is appreciated that certain features of the disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.